Field of the Invention
The present invention relates to a method for producing a metallic carrier body. The invention also relates to a metallic carrier body, in particular a catalyst carrier body for exhaust gas systems of internal combustion engines.
Metallic carrier bodies, which are also referred to as honeycomb bodies, in particular catalyst carrier bodies for exhaust gas systems of internal combustion engines, are known, for example, from International Publication Nos. WO 92/02717 and WO 92/02716.
A feature common to all of those bodies is that they are formed of a plurality of individual sheets or layers which are at least partially structured. The sheets delimit flow channels, through which an exhaust gas can flow. The sheets are wound or coiled one around the other in order to form individual gas channels.
The activity of a catalyst carrier body, which is disposed within an exhaust gas system of an internal combustion engine, depends, inter alia, on the flow conditions in a metallic carrier body. In order to improve the flow conditions, it is proposed, according to International Publication No. WO 92/02717, that at least part of the sheets have structures running approximately parallel to the direction of flow. In at least part of those structured sheets the structures have structure heights and/or structure widths narrowing continuously or in steps in order to form channels having different cross-sectional areas. Another proposal for improving effectiveness and/or the flow conditions in a metallic carrier body is described in International Publication No. WO 92/02716, mentioned above. According to that publication, it is proposed that, as seen in the direction of flow of the channels, the carrier body be constructed in such a way that the number of channels per cross-sectional area, and consequently the cross-sectional area of individual channels, vary in different portions located one behind the other in the direction of flow.
Such carrier bodies have high effectiveness and a favorable flow behavior, which is advantageous particularly in the case of large exhaust gas volumes.
Such metallic honeycomb bodies are produced by laminating at least partially structured sheets so as to form at least one stack. The laminated stack or laminated stacks are subsequently coiled at least partially one around the other. The stacks that are coiled one around the other are thereafter introduced into a casing tube. The carrier body which is thus produced subsequently has brazing material applied to it and is subjected to a brazing operation, with the result that the individual sheets are connected to one another. In addition, a connection may be made between the sheets or layers and the casing tube. The outlay for producing such carrier bodies is relatively high.